Dear Readers: A little science news today!
The annual Perseid meteor showers, which seem to radiate from the constellation Perseus, have been viewable to some extent since around July 17. But tonight, they are expected to be at their peak, with as many as 80 meteors streaking the sky hourly.
You can look up for them throughout the night tonight, but especially promising times are between 9 and 11 p.m. PDT, and before dawn on Wednesday morning, according to a NASA blog (by the way, this NASA post provides a fun 101 on meteors).
The Perseids are a prolific meteor shower associated with the comet Swift-Tuttle. The Perseids are so called because the point they appear to come from, called the radiant, lies in the constellation Perseus. Meteor showers occur when Earth moves through a meteor stream. The stream in this case is called the Perseid cloud and it stretches along the orbit of the Comet Swift-Tuttle. The cloud consists of particles ejected by the comet as it passed by the Sun. Most of the dust in the cloud today is approximately a thousand years old. However, there is also a relatively young filament of dust in the stream that was pulled off the comet in 1862. The rate of meteors originating from this filament is much higher than for the older part of the stream.
The Perseid meteor shower has been observed for about 2000 years, with the first known information on this meteor shower coming from the Far East. In early medieval Europe, the Perseids came to be known as the “tears of St. Lawrence.”